JPH0433479Y2 - - Google Patents

Description

[Detailed Description of the Invention] a. Field of Industrial Application The present invention relates to a vibration damping device for absorbing vibrations of a vibrating body, particularly to a vibration damping device for a bumper of an automobile.

b. Prior Art FIGS. 5 and 6 are conceptual cross-sectional views of a vibration damping device according to the prior art.

In the case of Fig. 5, the vibration of a member a vibrating at a frequency _a is caused by the vibration of a weight e connected to the member a via an elastic body d using bolts b, nuts c, etc., and the internal friction of the elastic body. It then attenuates.

The resonance frequency f _e of the weight e is the equivalent mass of the weight
M _e is determined by the equivalent elastic modulus of the elastic body K _d . Therefore, by adjusting the mass of the weight e, the elastic modulus of the elastic body, and the respective dimensions or materials, the resonance frequency f _e of the weight and the frequency of the member a can be adjusted.
f _a can be matched.

In the case of Fig. 6, the vibrating body g and the weight h are elastic bodies i
are connected via. Frequency f _g of vibrating body g
The natural frequency f _h determined by the mass of the weight h, the elastic modulus of the elastic body i, their dimensions, etc. is made to match. As a result, the vibrations of the vibrating body g and the vibrations of the weight h resonate, and the vibrations of the vibrating body g are attenuated.

c. Problems that the invention aims to solve: Conventional vibration damping devices use rubber as the elastic body, and adjust the elasticity of the rubber and the mass of the weight to match the resonant frequency to the frequency of the vibrating body, which eliminates variations. There are quite a lot of them, making production management difficult. A further disadvantage is that the weight is large, especially at low frequencies.

d Means for solving the problem The above problem is solved by using an automobile bumper vibration damping device as an elastic metal member for damping vibrations of a resin bumper 2 attached to the car body via two bumper brackets 3. A linear iron plate 1 is attached to the bumper 2 near both ends of the iron plate 1 between the bumper brackets 3.
A bumper for an automobile, comprising a collar and a screw as a fixing member to be fixed substantially parallel to a bumper 2, and characterized in that the natural frequency of bending vibration of the iron plate 1 is approximately equal to the natural frequency of bending vibration of the resin bumper 2. The problem was solved by a vibration damping device.

e Effect If the frequency of bending vibration of the above elastic metal member is ₁ and the frequency of vibration of the vibrating body is ₀ , the natural frequencies of the coupled system of the vibrating body and damper are ₁ + ₀ and ₁ - _0.
becomes.

In the present invention, adjustment is made so that _1≈2 , so _{1 + 0} ≒ _{20 and 1−0 ≒} 0. Generally speaking, the higher the frequency, the greater the amount of vibration damping inside the stationary station. Therefore, the vibration corresponding to frequency 2 ₀ is
Attenuation is severe compared to ₀ . On the other hand, ₁ − ₀ ≒
Since it is 0, the low frequency side branch does not appear as vibration. The vibration spectrum of elastic metal members has sharper peaks than that of rubber. Therefore, vibrations at a specific frequency can be more reliably damped than in the case of rubber.

f Embodiment FIG. 1 is a top view of a preferred embodiment of a vibration damping device according to the present invention attached to a bumper of an automobile, and FIG. 2 is an enlarged front view of FIG. 1.

The vibration damping device according to the present invention is attached to the lower part of a resin bumper 2, and the bumper 2 is attached to the vehicle body via a bumper bracket 3.

In the vibration damping device of this embodiment, a deformable iron plate 4 is fixed to a resin bumper 2 with screws 6 through a collar 5. The color is bumper 2 and iron plate 4
The purpose is to prevent contact with In order to prevent deformation of the bumper 2, deformation prevention flat washers 7a and 7b are arranged between the screw 6 and the bumper 2.

The natural frequency of this damping device is the elastic metal member 4
It is determined by Young's modulus, second moment of area, distance between bolts, mass density distribution, etc. Therefore, by appropriately selecting or determining these values, the vibration frequency of the bumper 2 and that of the vibration damping device can be made to substantially match.

FIG. 3 shows the attenuation spectrum of the vibration damping device versus frequency.

Since conventional vibration damping devices utilize the elasticity of rubber, internal friction is large and the spectrum is wide (dashed line). On the other hand, since the vibration damping device according to the present invention utilizes the elasticity of an elastic metal member, the internal friction is small and the spectrum is narrow (solid line). Therefore, vibrations of a given frequency can be reliably damped simply by vibrating the light elastic metal member.

g Effects of the invention Since an elastic metal member is used, the resonance peak is sharp, and vibrations can be effectively damped simply by vibrating a light member.

Since the elastic metal member and the vibrating body are tightly coupled, vibrations are efficiently transmitted and reduced.

Since no rubber is used, there is little variation and quality control is easy.

Since the structure is simple, the cost is low and it is lightweight.

[Brief explanation of the drawing]

Fig. 1 is a top view of a preferred embodiment of the vibration damping device according to the present invention attached to the bumper of an automobile, Fig. 2 is an enlarged front view of Fig. 1, and Fig. 3 is attenuation of the vibration damping device with respect to frequency f. 4 and 5 are conceptual cross-sectional views of a vibration damping device according to the prior art. 1... Vibration damping device, 2... Bumper, 4, 4a...
...Teppan, 5...Color.

Claims (1)

[Scope of utility model registration request] A vibration damping device for an automobile bumper for damping vibrations of a resin bumper 2 attached to a vehicle body via two bumper brackets 3 includes a linear iron plate 1 as an elastic metal member, and the iron plate 1.
It consists of a collar and a screw as a fixing member that fixes the steel plate 1 to the bumper 2 in the middle between both bumper brackets 3 in the vicinity of both ends of the bumper bracket 3, approximately parallel to the bumper 2. A vibration damping device for an automobile bumper characterized by a vibration damping device having a vibration frequency approximately equal to the natural frequency of bending vibration.